1. Field of the Invention
The present invention relates to a chloroisocyanurate composition for disinfection and sterilization, more particularly, to a composition comprising a dichloroisocyanurate, which may be used to prevent an increase in hydrogen ion concentration and which has excellent stability during storage.
2. Decription of the Prior Art
Dichloroisocyanurates have been widely used due to the fact that since active chlorine (residual chlorine) supplied in water is stable as compared to a sodium hypochlorite solution or highly bleaching powders (main ingredient: calcium hypochlorite) and thus only a small amount is required, they are free from calcium hydroxide or calcium carbonate as in highly bleaching powders, and they are completely soluble and have a potent bactericidal activity. For example, bactericidal disinfectants or slime controlling agents for sewage, pool water, cooling water, etc. in the form of powder granular, tablet, etc. preparations.
However, in the case that dichloroisocyanurates are supplied continuously or intermittently over long periods of time for sterilization, disinfection or slime control of water which is in a closed system, for example, cooling water, pool water, etc., dichloroisocyanurates accumulate in reservoir water frequently causing an increase in hydrogen ion concentration in the water. This tendency is particularly significant in water having low alkalinity, such as rain water. Furthermore, in water such as cooling water which is recycled over long periods of time and relatively easily polluted, the amount of dichloroisocyanurates to be supplied is increased so that the hydrogen ion concentration in the water also increases. When the hydrogen ion concentration increases, corrosion of equipment, etc. occurs.
For these reasons, a method of periodically sprinkling sodium carbonate has been adopted to prevent such an increase in hydrogen ion concentration in water in a closed system. However, supplying sodium carbonate while measuring pH and controlling the amount of sodium carbonate is complicated.
Extensive studies have not been made as to how to prevent an increase of the hydrogen ion concentration due to continuous use of dichloroisocyanurates in a closed water system as described above. A method has been proposed in Japanese Patent Laid-open Publication No. Sho 59-67208 (67208/1984) in which isocyanuric acid and magnesium oxide or magnesium hydroxide are formulated in trichloroisocyanuric acid. However, when using this method in a closed water system over long periods of time, the pH of the water may gradually decrease. Furthermore, there has been proposed a trichloroisocyanuric acid composition having formulated therein an alkaline substance. However, this composition is unstable when in a moistened state (wet state), such that it generates nitrogen chloride gas having explosive properties. That is, care must be taken when handling the composition and during storage of the composition, wetting should be strictly prohibited.